Sample size determination for cardiodynamic ECG assessment using the Concentration-QTc analysis method

Concentration-QTc (C-QTc) analysis was accepted to serve as an alternative to the by-time point analysis with intersection-union test (IUT) as the primary basis for decisions to classify the arrhythmogenic risk of a drug by ICH E14 Q&As (R3) in December 2015. Since then, this analysis method has been widely applied by industry as it significantly reduces the sample size to achieve the same power as with IUT. There are many model-based power calculation approaches available for C-QTc through simulation in the literature, however, there is still no standard method with a clear formula to determine the sample size for C-QTc analysis to exclude a small effect on the QTc interval. The current model-based simulation approaches are too complicated to prevent them from being widely used, which is not commensurate with the popular status. We have developed a systematic method based on t-tests to determine the sample size for different study designs using the C-QTc analysis method and applied it to many studies. The results of the sample sizes utilizing this method are consistent with simulation studies and validated by real analyses.